Radio direction finding system



Nov. 26, 1940. B. KALZ 2,223,069

RADIO nnmc'non FINDING SYSTEM Fiied May 11, 1959 FIGJ.

IN VEN TOR.

BRO/V0 lfflLZ I A TTORNE Y.

Patented Nov. 26,1940

.1 p 2323,669 RADroDIREo'rIoN FINDING-SYSTEM I Bruno Kalz, Dabcnd'orf, KreisvTeltow, Germany,

assignorto O. Lorenz Aktiengesellschaft,;Berglin-Tempelhof, Lorenzweg, Germany, a com- Application May 11, 1939';- Serial No. 272,971

" In Germany May- 17, 1938 a v f 1 ,s'caims- (erase- 11);

' This invention briefly relates to radiodire'ce,

' 't ioin finding systems, and more particularly inprovements'in or releating to radio receivers for obtaining bearings.

Several direction findingfireceiver systems are' known in the art, and one type of such devices I operates with a'directional frame antenna" and'a. I non-directional auxiliary antenna, which two antennav means are alternately caused to operate in phase coincidence and phase opposition. The

field intensities of electromagnetic waves -.ra-'- d iated from a non-directional transmitterand picked up by the frame antenna and the auxiliary antenna in their state of phase coincidence or phase opposition are then compared with-one another either acoustically in a telephone receiver, or optically by means of an indicating ina strumentgfor example, in order to determine the 7 position of the receiver relative to the transmitter. The abovementioned alternate operation of the antenna means in phase'coincidence' and phase opposition is preferably effected in such 1 manner that the phase of the frame antenna is (subjected toa' reversal in a change-over device, 25 while the auxiliary non-directional antenna is continually maintained coupled with the input circuit of the receiver; In' response 'to the operation of the change-over device, differently' diy 'rected and mutually intersecting'idiagrams of cardioi-dal shape are alternately produced, wh'ere by'the straight line traced through the points 'ofintersection of the diagrams and through the center point of the receiving system defines-the maximum-direction of action or course line.

The maximum direction of action of the heretofore'used direction finding systems'is' effective perpendicular to the plane of'the frame antenna or aerial; Because of the fact' that this frame antenna; when installed on an aeroplane, gen- 40 er'ally formslrightangles withthe longitudinal axis cf'the'aero-plane, this axis exactlycoincides with the direction of maximumaction, that is,

,is laterally displaced by a sudden squall. It .is therefore highly desirable to provide means for rendering this relationvariable in response to vthe direction and the intensity of the wind in order to compensate for such'lateral 'displacementv by introducinga corresponding angular correction. The, provision-ref, a. rotatable frame,

aerial'for such correction wo-uld neither be an economical .nor a practical measure, since apart from the expenditure per se for rotatable frame aerials, also the comp1icatedrneans must be borne in mind which I are" necessarily required "6 for remotely controlling the angular position of the frame aerial from the'pilots position. The same; considerations apply to similaninstalla tionsion ships. g i Y It" is an object-of this inventionto provide 10 "new and useful means which in a simple and reliable manner perform the'aforementioned angular correction at a minimum of additional ex penditure. -This' is realized according to the main feature of this invention byTvoluntarily changing thev potential conditions of the an- -tenna'system or input-circuit of a direction *find- I ing receiver in order tolobtain asymmetric; -receiving diagrams 'for subjecting the maximum of directional reception actionto anangular 'rotation with respect to the center of the-receiving system. In accordance with a further "fea- .ture offlmy invention, the amplitude of "the effective voltage o'f the auxiliary non directional antenna is changed simultaneously with a 1re- 25 vversalofthe phase condition of the frarne' antenna.i-. The amplitudeflchange thusuimparted' to the auxiliary antenna is preferably made var ia-ble; e. 'g., by thea'gencyof ,a'variable impedance in order to provide the possibility for ar- 'bit'rarily correctingthe angle between the line of maximum direction of action and the longitudinal axis of the airplane in either direction. In, one specific aspectof my invention, the change of the auxiliary antenna potentialis efiected con- (3 connecting fro-msaid auxiliaryantenna aground I 1 potential which is'adjustable at will by 'me'ansu of a variable differential condenser. v 40 I The invention will be more readily understood from the following, description taken in conjunction with the accompanying drawing, .inwhich' Fig. 1 schematically shows one arrangement embodying my invention, while Fig. 2 shows diagrams obtained by the arrangement according to Fig.1. I a

Referring toFig. 1, reference numeral l'indicates a frame antenna or aerial-while reference numeral. 2 denotes a 'nOfi-directiOnal-auxiliary "antenna. Mutually .intersectiing reception diagrams are produced alternately by reversing the phase conditions .ofthefframe aerial I by means ,of a change-over device 3. The frameaerial :l;

is coupled to the input circuit Soi'the receive'r orries ,t

differential condenser 9, causes the circular diagram of the auxiliary anthrough an intermediary coupling circuit 4, while the non-directional auxiliary antenna is continually coupled with the input circuit through a coupling coil 6. The phasal relation between the auxiliary antenna and the frame antenna is adjusted in a known manner by means of 21. variable resistor T. The potential of the auxiliary antenna 2 is according to the main feature of my invention changed concurrently with a phase reversal in the frame antenna due to the operation of the changeover device 3. This potential change is performed by switching means 8, e. g., in the form of a make and break contact which is mechanically coupled with the changeover device 3. The two switch means 3 and 8 may also be designed as rotatable switches. During the phase reversal in the frame antenna 3, the switch means 8 connects the auxiliary antenna 2 to ground over variable condenser 9 with the result that the potential of the last mentioned antenna is reduced. It is obvious that this facility introduces an asymmetry in the diagrams from which follows that the direction of maximum action is angularly displaced.

The variable condenser is preferably designed as a differential condenser, the rotatable spindle .of which is so coupled with a further switching device ID, that the last mentioned device is actuated in the minimum or neutral position of the differential condenser for connecting either of the stator plates of this condenser to the con:

diagram of the frame antenna I is shown at H.

The auxiliary antenna 2 at full voltage produces the circular diagram I2. The diagram ll of the frame antenna in cooperation with the diagram .l2 of the auxiliary antenna produces the cardioidal diagram l3. In response to a phase reversal in the frame antenna and a potential decrease in the auxiliary antenna by Virtue of the actively connected condenser 9, also the circular diagram of thisantenna is reduced so as to correspond with that shown at M. In response to the cooperation between the frame antenna diagram II and the circular diagram I4 of the auxiliary antenna, the resultant diagram I5 is produced. The diagrams l3 and I5 thus produced .in response to the alternate manipulations here tofore described are effective in the input circuit of the receiver and the point I6 at which the two last mentioned diagrams intersect is decisive for the maximum of directive action. The longitudinal axis of the airplane and the direction of movement thereof is indicated by arrow ll, while reference numeral l8 indicates the angle of correction thus obtained according to myinvention. This angle l8 of correction may be increased by increasing the capacity of the since such increase tenna to decrease with the result that the circular diagram l4 decreases and displaces the point I6 of intersection still more to the right side. With the condenser 9 in its minimum or neutral position, the direction of maximum action coincides with the longitudinal axis of the aeroplane. If the differential condenser is rotated to the other side, this condenser becomes active in the other phasal condition of the frame antenna. l by virtue of the switching device It), the position of which depends upon the position of the condenser spindle. In consequence to this last mentioned procedure, the angle of correction is moved or displaced to the other side of the longitudinal axis I I of the aeroplane.

In order to still increase the capability of adjustment, additional measures may be carried out in order to likewise reduce the potential of the frame antenna during a phase reversal in said antenna. Such measures may be accomplished in a similar manner and by similar switch means, shown at 2| in Fig. 1, as heretofore described for changing the potential conditions of the auxiliary antenna. The advantage which may be obtained by also subjecting the frame antenna to a potential change consists in the fact thatthe angular correction heretofore mentioned may be extended over a larger angular range.

What is claimed is:

1. In a radio direction finding receiver, an input circuit, a directional frame aerial coupled to said input circuit, a non-directional auxiliary antenna likewise coupled to said input circuit,

switch means connected to said frame aerial for alternately reversing the phasal relations between said frame aerial and said auxiliary antenna from phase coincidence to phase opposition, and vice versa, further switch means connected with said auxiliary antenna for changing the potential thereof during a phase reversal, and means ,to variably apply ground potential to said auxiliary antenna to a point on said antenna above said input circuit coupling in response to the operation of said further switch means for selectively adjusting a potential change of said auxiliary antenna to any desired value.

2 The invention according to claim 1, characterized in that said means adapted to variably apply ground potential to said auxiliary antenna is a differential variable condenser, connected between ground and the said further switch means.

3. In a radio direction finding receiver, an input circuit, a directional frame aerial coupled to said input circuit, a non-directional auxiliary antenna likewise coupled to said input circuit, switch means connected to said frame aerial for alternately reversing the phasal relations between said frame aerial and said auxiliary antenna from phase coincidence to phase opposition, and. vice versa, further switch means connected with said auxiliary antenna for changing the potential thereof during a. phase reversal, means adapted to variably apply ground potential to said auxiliary antenna in response to the operation of said further switch means for selectively adjusting a potential change of said auxiliary antenna to any desired value, and means for interconnecting said switch means connected to the frame aerial and said further switch means mechanically for concurrent operation.

4. In a radio direction finding receiver, an input circuit, a directional frame aerial coupled to said input circuit, a non-directional auxiliary antenna likewise coupled to said input circuit, switch means connected to said frame aerial for alternately reversing the phasal relations between 'saidframe aerial and said auxiliary antenna from phase coincidence to phase opposition, and

vvice versa, and means' to variably apply ground 'potentialto said auxiliary antenna. for changing the'efiective potential thereof during a phase reversalcomprising, a variable impedance in the form of a differential condenser having two stator plates and a rotatable spindle carrying one grounded rotor plate adapted to cooperate with eitherof said stator plates, a contact arm electri cally connected with said auxiliary antenna and mechanically. coupled with said switch means 'for concurrent operation therewith, two contact, terminals adapted to be intermittently connected with said antenna in response to the operation during .a phase reversal.

contact arm;

5.- The invention according to claim 4,charac I I terized in that additional means are provided 10' frame: aerial for varying the potential of said B UNO KALZ. 

